Wednesday, February 27, 2013

Printing protocols Printer Basics

Since the 70s, a time when printing was just committing ASCII text to paper line by line, the LPD protocol is used to control the printers output. Printing became a more and more sophisticated job by a growing variety of text formatting options and the addition of pictures,
today even of a photo-realistic quality. This is why time and again each manufacturer added his own extensions to LPD and the different specifications usually were incompatible to each other.
Now a new protocol is ahead, the Internet Printing Protocol IPP. IPP is on its way to establish a common standard for all the different printing devices and operating systems and therefore will enable comfortable printing across any network from LAN to the Internet. IPP bases on HTTP, the well-known WWW standard. In the same way HTTP transmits web pages containing text, pictures, sounds, script code etc. from a server to a client or e. g. a forms data from the client to the server, HTTP is able to transmit any kind of data needed for network printing. Clients, printers, print jobs, and even administration assignments and status queries can be identified by URIs (Uniform Resource Identifiers). A HTML based user interface can make printers and their configuration options available by an ordinary web browser. Apart from the network abilities IPP will make several new features available:
• A client doesnt need to send a file to the printer (push method),
the client simply directs the printer to fetch the file from where it is
stored (pull method).
• A client is able to find any of the networks printers, even when a
printer is unknown to the client so far.
• A client is able to get detailed information about a certain printer.
• A printer is able to start a print job before all of the print jobs data
have arrived.
• A single print job can consist of several documents.
• Printers and print servers can be configurated from any point of
the network.
• Printing across a network, especially across the Internet, will be
save, because transmitted files can be encoded and users can be
obliged to authenticate themselves.
Today already about a hundred products from printers to applications provide IPP abilities and a first IPP application, CUPS (Common UNIX Printing System), is available for UNIX based networks.

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